Explore the cosmic microwave background in this 28-minute talk by Ruth Durrer, part of the Workshop on "Blackbody Radiation Induced Effects and Phenomena" at the Erwin Schrödinger International Institute for Mathematics and Physics. Delve into the best-measured blackbody radiation at a temperature of 2.72548 ± 0.00057K, examining its significance in observational cosmology. Discover the importance of its near-perfect isotropy, small anisotropies, and polarization. Learn about the radiation's spectral stability and potential deviations from a blackbody spectrum expected in future experiments. Journey through the history of the universe, covering topics such as nuclear synthesis, dark ages, and the origins of fluctuations. Gain insights into angular scales, the Hubble parameter, and other key cosmological parameters derived from cosmic microwave background data.